The invention concerns the machining of workpieces in a machine tool by means of a plurality of machining processes. Here different tools are used for the individual machining processes. The tools come into use one after another. Here not only tools of one and the same category come into consideration, such as for example milling cutters, but also tools of different categories, for example milling cutters, drill bits, and so on.
The tools are stored in a tool magazine. Here this can, for example, take the form of a turntable, on the circumference of which a large number of drill bits, milling cutters, and so on are suspended in the vertical position. Such a magazine is a component of a tool changer, which supplies a particular tool to the machine tool at a particular point in time. In this manner a machining programme is executed in a particular sequence with various tools and machining times.
When one talks here of a “machine tool” it is, of course, to be understood that this can also include a machining centre of a state-of-the-art form of construction, with which any chip removal machining processes can be executed.
An essential element of any machine tool with chip removal machining is the cooling, lubrication and washing system. With this both tool and workpiece are cooled and washed, that is to say, chips are removed from them. If this is not executed in a perfect manner, damage to both tool and workpiece can occur. Particularly serious are incidences of damage that cannot be immediately detected when they occur. An extremely important aspect is the cost of the tools. Thus a carbide milling cutter can, for example, cost several hundred euros. Washing is of fundamental importance for the service life of the milling cutter. This can be counted in hours, but also in minutes, or even in seconds. Decisive factors determining the service life are the washing and cooling.
Thus the washing must on the one hand be efficient. This means that the flow rate of the washing medium has to be sufficient, that is to say, sufficiently high to capture all the chips, even chip particles of minimal dimensions. On the other hand the washing process must be economical, that is to say the washing medium must not be supplied in excess, since the supply power is an important item in the cost analysis. This applies particularly to fluids, but also to air as a washing medium.
The efficiency depends to a very considerable extent on the washing jet of the medium impinging at the right location, in particular at the site at which the chip is being removed. The medium jet should thus always emerge at the correct angle from the nozzles of an appropriate nozzle body, so that it impinges at the correct location. However, this is exactly what is not always the case.
The reason for this lies in the fact that the tools have different dimensions, for example, they are short or long, or thick or thin. This was dealt with previously by directing the one or more medium jets on to one point, which in terms of average dimensions is the correct location. Since this can only be an approximate solution, an attempt is made to compensate for this deficiency by increasing the flow rate. The economics of the washing process suffer in turn as a result.
It would of course be possible to adjust the jet exiting from a nozzle body to another angle when the tool is changed. However this is not possible in practice, since it is bound up with personnel costs and is completely contrary to the concept of rationalisation. Also the accuracy of manual adjustments is insufficient.
US 2005/0169718 A1 describes a cooling device for the supply of a coolant to a tool. Here provision is made for a plurality of cooling devices for the various tools, with one application for each device, and particular attention is paid to fitting. Coolant impinges over the whole length of the tool.
The object of the invention is to define a method and a device with which it is possible to equip a machine tool in the most general sense with tools such that the point of impingement of the one or more medium jets is always correct, thus in general the site of the chip removal, and moreover such that the washing and cooling process takes place with a minimum use of energy and is thus as cost-effective as possible.